The invention relates to a process for preparing amine-modified polyester resins with improved melt flow.
Polyesters and copolyesters, as well as their blends with other thermoplastics, are used to make a range of products that includes injection molded parts, films, blow-molded goods, and pultruded sheets. These articles are used in automotive, electrical and electronic applications. The mechanical strength, electrical insulation and easy processability are some of the key characteristics of polyesters which enable their use in these applications. The current industrial trend is toward the fabrication of parts, with complicated and fine designs, with small flow cross-sectional areas where the fluidity of conventional polyesters has been found inadequate.
To address the demanding requirements of high melt flowability, a polyester resin can be replaced by another polyester resin having lower viscosity. Thus there exists a need to prepare a wide variety of high flow polyester resins in a simple, low cost manner that can be applied to both large and small scale continuous production. Further, the process should be environmentally friendly using no solvent. Furthermore, the process should be accomplished without the need for large scale chemical plant construction or capital investment. In other instances there is a need to convert high viscosity polyester compositions into lower viscosity compositions through a simple low cost melt process.
U.S. Pat. Nos. 7,825,176, 7,405,250, and 7,405,249 disclose polyester compositions with high flowability. The compositions comprise a polyester and an alcohol that acts as a flow enhancer. A need remains, however, for processes to make amide functionalized polyester compositions with high flowability that rely on non-alcoholic flow enhancers.